Messages sent via clacks show as 'edited' even when not edited

[islewis]

Description

When sending a message via clacks send, the message appears in Slack with an "edited" indicator even though no edit was performed.

Steps taken

1. Sent a single message to #infra-prs-only:

   clacks send -c infra-prs-only -m "https://github.com/magicproduct/terraform/pull/12224"

2. Response from clacks:

   {"ok": true, "channel": "C078HM9AWLV", "ts": "1769647800.284909", "message": {"user": "U08RX5EKSTF", "type": "message", "ts": "1769647800.284909", ...}}

3. No subsequent commands were run on this message - no clacks edit, no second clacks send to the same channel/thread

4. The message appeared in Slack with an "edited" indicator

Expected Behavior

Messages should not show an "edited" indicator unless they were actually edited.

Actual Behavior

The message displays with Slack's "edited" label immediately after being sent, despite only a single clacks send command being executed.

Context

This was observed while using the /watch-scalr skill in Claude Code, which sends a PR URL to #infra-prs-only after Scalr plans complete. The full session involved other clacks commands to different channels, but the message to #infra-prs-only was a single send with no edits:

Commands run in session (in order):

1. clacks send -c infra-prs-only -m "https://github.com/magicproduct/terraform/pull/12224" ← This message showed as edited

Only command #1 touched #infra-prs-only, and it was a single send with no edits.